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Hemangiomas are true tumors with pathologic endothelial cell proliferation; vascular malformations are distinguished by this distinct absence.
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HEMANGIOMA OF INFANCY
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ESSENTIALS OF DIAGNOSIS
Absent at birth or history of small premonitory mark at birth.
Rapid neonatal growth of the lesion.
Cutaneous lesions develop either a typical “strawberry” appearance or a bluish hue (“deep bruise” appearance).
Magnetic resonance imaging (MRI) is diagnostic when the diagnosis is uncertain or when serial exam is not possible.
Visceral involvement is suspected if there are more than 3 cutaneous lesions.
Progressive stridor in the appropriate age group (2–9 months) is suspicious for airway hemangioma.
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General Considerations
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Hemangiomas are the most common tumors of infancy. They are more common in females than in males (3:1), in white populations, and in premature infants. Most of these neoplasms are located in the head and neck. Additionally, most are single lesions; however, about 20% of patients have multiple lesions. Hemangiomas exhibit a period of rapid postnatal growth. The duration of the proliferative period is variable, but is usually confined to the first year of life. The proliferative period rarely extends to 18 months. The involutional phase is also quite variable, occurring over a period of 2 to 9 years. After complete involution, normal skin is restored in about 50% of patients. In other patients, the skin may show evidence of telangiectasia, yellowish hypoelastic patches, sagging or fibrofatty patches, and scarring if the lesion has ulcerated.
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Hemangiomas can be classified as superficial (Figure 7–1), deep (Figure 7–2), or combined. The term superficial hemangioma replaces the older terms capillary hemangioma and strawberry hemangioma and refers to hemangiomas located in the papillary dermis. The deep hemangioma, often slightly blue in color, originates from the reticular dermis or the subcutaneous space and, in the past, was referred to as a cavernous hemangioma. The combined hemangioma has elements of both the superficial and the deep hemangioma.
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Proliferative hemangiomas have been shown to express high levels of indolamine 2,3-dioxygenase (IDO), basic fibroblast growth factors (β-fgf), proliferating cell nuclear antigen, type IV collagenase, urokinase, and, most recently, insulinlike growth factor 2. Involuting hemangiomas have been characterized by exhibition of tissue inhibitor of metalloproteinase-1 (TIMP-1), thrombospondin, interferon-α, and decreased levels of other factors seen in the proliferative hemangioma.
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In addition, it has recently been shown that endothelial cells are of clonal origin and the defect that leads to tumor growth and the altered expression of growth factors is intrinsic ...